Refrigerating machine



Mafch1 1,1941. I C,STEENSTRUP v 2,234,711

REF'RIGERATING momma Filed Dec. 1. 1937 4 Sheets-Sheet 1 Fig 1.

9 a 23 v I 24 \25- Inventor- Ci'wistzizmv jteenstrup,

" His Attorney.

c. STEENSTRUP 2234,71]

REFRIGERATING MACHINE Filed Dec. 1, 193'? 4 Sheets-Sheet 2 Inventori 1 Christian Steenstrup,

by flan/17C? His Attorney.

March 1941- c. STEENSTRUP REFRIGERATING MACHINE Filed De c.

, 1937, 4 Sheets-Sheet 5 DH m W w n 0 P t 0 msdw v 6 1mm MAM Y March 11, 1941. c $TEEN$TRU|= 2,234,711

REFRIGERATING MACHINE v Filed Dec'. 1, 1937 4 Sheets-Sheet 4 I I II II Willi] Ifiventor Christian Steenstrup,

y His Attorney.

' air in the food compartment'may not circulate Waterti ht it, 1941 STATES 2,234,? ill REFRIGERATING MACHINE New York Application December 1, 1937, Serial No. lii'ALQS 9 Claims.

My invention relates to refrigerating machines and particularly to such machines having cooling units arranged to provide a plurality of zones operating at different temperatures.

Refrigerating machines, and particularly household refrigerators, are commonly provided with evaporators which are designed to provide adequate surface to cool the air in the cabinet and also a low temperature zone in which water, dessorts, and the like may be frozen. Some evaporators for this purpose have been designed to have separate sections in which the refrigerant is maintained at different pressures in order that the evaporator may inherently provide different temperature zones. The freezing zone is frequently separated from the air cooling zone by insulated walls or other means in order that the through the freezing zone where a substantial quantity of moisture would be removed from the air. The rate ofdehydration of food in the refrigerator cabinet is minimized since the cabinet evaporator may be maintained at temperatures well above the freezing zone. It sometimes is desirable to provide more than two diiferent temperature zones since some foods, such as meats, are better preserved at temperatures intermediate the temperature of the food compartment and 'that of the freezing chamber. Accordingly, it is an object of my invention to provide a refrigerating machinehaving an improved cooling unit for establishing a plurality of cooling zones in a refrigerator cabinet.

Another object of my invention is to provide a refrigerating machine including an evaporator having a plurality of sections and an improved arrangement for maintaining each of said sections at a different temperature.

A further object of my invention is to provide an evaporator of the flooded type for maintaining a plurality of different temperatures and having an improved arrangement for circulating refrigerant therein.

Further objects and advantages of my invention will become apparent as the following description proceeds, and the features of novelty which characterize my invention will be pointed out with particularity in the'claims annexed to and forming a part of this specification.

For a better understanding of my invention, reference may be had to the accompanying drawings in which Fig. lis a front elevation of the upper portion of a household refrigerating machine embodying my invention; Fig. 2 is an enlarged sectional view of the evaporator shown in Fig. 1 taken on the line 2-2; Fig. 3 is an enlarged perspective view of the evaporator shown in Fig. 1 with the freezing chamber thereof shown removed therefrom; Fig. t is an enlarged sectional View of the pressure regulating valve of the 5 evaporator shown in Figs. 1 to 3; Fig. 5 is a perspective view of a modified form of an evaporator embodying my invention shown with the control panel and freezing portion removed; Fig. 6 is a sectional view on the line t-t of Fig. 5, the 10 evaporator being shown assembled; and Fig. 7 is an enlarged view of the pressure controlling valve of the evaporator shown in Figs. 5 and 6.

Referring now to the drawings, in Fig. l I have showna refrigerating machine including a cabinet Hl having a food compartment ll normally closed by a door (not shown) and a cooling unit I2 arranged within the compartment H. A condensing unit comprising a closed casing l3 within which is arranged a motor and compressor and a condenser it having a refrigerant conduit i5 mounted on a removable top it of the cabinet Hi. Gaseous refrigerant is compressed by the compressor within the casing l3 and discharged into the conduit it where it is cooled and liquefied by the natural circulation of air over the conduit, the liquid refrigerant flowing through a connection I! into a receiver or float valve chamber 18. When a predetermined quantity of liquid refrigerant has collected in the chamber 18, a float therein rises and the liquid refrigerant flows through a pair of conduits ill to the cooling unit i2. The liquid refrigerant within the cooling unit ii! is vaporized by the absorption of heat from the air within the compartment ii and from articles placed within the cooling unit, and the vaporized refrigerant is withdrawn through a suction line 20 and returned to the casing it. The refrigerating machine is provided with a control mechanism 2| having a thermostatic element 22 secured adjacent the outer portion of the cooling unit 12, the motor within the casing i3 being started and stopped by the control mechanism 2! in response to the temperature of the thermostatic element 22. The refrigerating machine thereby maintains the outer portion of the cooling unit l2 within a predetermined range of temperature. The range of temperature may be selected so that the outer evaporator rises to a temperature above freezing during each cycle and thus prevents the formation of any substantial quantity of frost. This is known as the defrosting cycle. The outer evaporator may be maintained above freezing at all times, if desired.

The cooling unit I? as shown in Figs, 1, 2 and 3 comprises an outer refrigerated portion or evaporator constituting a closed chamber and comprising a housing formed by inner and outer complementary sheets of metal 23 and 24 and a bottom sheet 25 and divided into two sections by a horizontal partition 26 near the middle thereof. The upper and lower sections thus formed are closed at the front by doors 2! and 28 respectively and the upper section is closed at its top by the top wall of the food compartment. The housing is suspended from the top wall of the food compartmenrt II on flanges I, 8 and 9 formed one on each of the three walls of the housing.

In order to cool the air within the food compartment II and within the upper and lower sections of the cooling unit, I provide headers 29, 30 and 3| in the upper portions of the three walls of the housing and refrigerant circulating conduits 32, 33 and 34 communicating with and depending from the headers 29, 30 and 3| respectively, and extending above and below the partition 26. The headers 29, 30 and 3| are designed to be maintained substantially half filled with liquid refrigerant. and they communicate with each other above and below the level of liquid refrigerant at the corners of the walls, the three headers as shown being formed as a continuous header around the three sides of the housing. The several refrigerant circulating passages and headers are formed as indentations in the sheet 23 while the sheets are flat. The sheets are then secured together by welding or brazing or any other suitable manner around their edges and around the indentations and are then bent to form the three-sided housing. In order to supply liquid refrigerant to the cooling unit I 2 and to produce a circulation of liquid refrigerant, I connect the supply lines l9 so that they inject refrigerant into the passages 33 and 34 and produce a circulation refrigerant therein. In order to increase the area of the cooled surface of the evaporator unit, I provide a plurality of fins 35 formed of channel-shaped members secured to the outer surface of the three walls of the housing.

In order to constitute the upper section a freezing chamber or compartment, I provide an evaporator comprising upper and lower refrigerated shelves 36 and 31 spaced apart and secured on brackets 38 and 39 within an open ended rectangular casing 40. The shelves 36 and 31 are provided with headers 4| and 42 respectively, and a plurality of refrigerant passages communicating therewith. The arrangement of the passages in the two shelves is the same and can be seen from the illustration of the lower shelf 31., A U-shaped passage 43 is provided extending around the sides of the shelf 31 and communicating at its two ends with the ends of the header 42 and two smaller U-shaped passages 44 are arranged within the shelf inside the area enclosed by the passage 43 and ducts 45 are provided at the midpoints of the passages 44 to provide communication between the passage 43 and the passages 44. In order to provide an adequate circulation of liquid refrigerant through the passages of the shelves, I inject refrigerant into the outer U-shaped passages of the two shelves through refrigerant supply injectors 46 and 41 of the upper and lower shelves respectively. A portion of the outer 'U-shaped passage of the upper shelf 36 can be seen in Fig. 3 as indicated at 48. Refrigerant is supplied to the shelf evaporators in suificient quantity to maintain the shelves flooded, the liquid refrigerant normally half filling the headers 4| and 42.

unit l2 on the spacers 50, so that the walls of the casing are spaced from the walls of the outer housing and form the partition 26. This, in effect, provides an insulating air space between the freezing chamber and the food compartment II and between the upper and lower sections of the housing thus partially insulating the sections and limiting the transfer of heat from the lower section to the upper section. In order to maintain the shelves 36 and 31 at sharp freezing temperatures, and the outer walls of the casing at temperatures required for a defrosting cycle or above freezing, I provide a pressure reducing valve 5| in a refrigerant connection 52 which communicates with the header 30 46 and 41, and provides a between the evaporators.

passage for refrigerant The connection 52 of liquid refrigerant therein. Therefore, when gaseous refrigerant is withdrawn from the header through the connection, any excess liquid refrigerant is withdrawn therewith and both liquid and gaseous refrigerant flow from the header through the valve 5| into the inner evaporator. The degree of opening of the valve 5| may be varied by turning a handle 53. It will be evident that the outer evaporator comprising the conduits and headers formed on the outer housing may be maintained at a different pressure than the inner evaporator comprising conduits and headers of the shelves within the inner casing by restricting the passage of refrigerant between the two evaporators. Since the refrigerant is first admitted to the outer evaporator, thence flows through the valve 5| to the inner evaporator and is withdrawn from the inner evaporator by the compressor, the inner evaporator will be maintained at a lower pressure than the outer evaporator and hence at a lower temperature, the difference in temperature being determined by the setting of the valve 5 I. Since the refrigerating machine is controlled in response to the temperature of the outer evaporator, that temperature will remain substantially constant and, by changing the setting of the valve 5|, the pressure within the inner evaporator and, hence, the temperature and rate of freezing of fluids placed therein can be regulated as desired. The construction of the valve 5| is clearly shown in Fig. 4 in which I have shown a sectional view. A needle valve 54 is arranged to seat in an opening 55, the position of the valve with respect to the opening being adjusted by the handle 53, so that any desired degree of opening may be obtained. An indicating dial 55 is provided on the shaft of the handle 53 to indicate the position of the valve 54, a stationary pointer 51 cooperating with the dial 55. The dial 56 may be calibrated in any suitable manner in order to indicate the relative temperatures of the evaporators.

I have found it desirable to provide an arrangement to prevent the complete shutting off of communication between the inner and outer evaporators, so that there is always some degree of refrigeration in the outer evaporator even though the diiferential temperature is set at its highest value. I, therefore, provide a small byand with the injectors assau t pass opening 58 around the valve opening 51 so that there must be at least a minimum opening at all times providing at least a restricted measure of communication between the conduits of the outer evaporator and the freezing shelves.

The size of the opening 58 should be selected so that the outer evaporator will not rise above a predetermined desired temperature even though the evaporators are working at the greatest differential of pressure. It will be understood readily by those skilled in the art that if the valve is permitted to shut off entirely the flow of refrigerant between the evaporators, then the temperature of the outer evaporator would rise and continuously call for cooling, thereby reducing the pressure within the inner evaporator to a minimum without reducing the pressure in the outer evaporator, This condition is obviously undesirable since the tempera ture of the outer evaporator and, hence, the temperature of the food compartment could not be controlled during the freezing period.

During the operation of the refrigerating machine shown in Fig. 1, the temperature of the outer walls of the cooling unit I2 will be regulated by the control device 2| and the refrigerating machine will operate to remove refrigerant from the inner evaporator to maintain a lbwer temperature therein as determined by the setting of the valve 5|. The doors 21 and 28 prevent the circulation of air from the food compartment over the colder portions of the cooling unit,

and, therefore, minimize the dehydration of air and food within the cabinet. The lower section of the cooling unit closed by the door 28 is maintained at a lower temperature than the air within the cabinet i i since it is arranged intermediate the cabinet H and the freezing chamber. The refrigerating effect of the lower portions of the coils 3t, 33 and 34 maintain the small amount oi air within the lower section at a relatively low temperature as compared with the temperature of the cabinet air surrounding the cooling unit,

. but not as low a temperature as that maintained inthe upper section of the housing by operation of the freezing shelves therein. During normal operation of a. refrigerating machine such as that illustrated, the cabinet air-might be maintained within a range of temperatures between 45 and 50 F. and the freezing chamber or compartment within a suitable range ofv temperatures below freezing. The range of temperatures maintained within the lower section of the housing may vary between 35 and 45 F., which is a suitable range for the preservation of such foods as, meats.

In Figs. 5, 6 and '7, I have shown a cooling unit embodying a modified form of my invention. This cooling unit may be arranged within a cabinet of a refrigerating machine in the same manner as the cooling unit shown in Fig. l. The cooling unit comprises an outer housing formed of inner and outer complementary metal sheets titand it respectively, and comprising three walls forming the sides and back wall of the cooling unit, flanges ti, 62 and G3 are formed at the tops oi the walls to support the unit within a refrigerator cabinet in such a manner as to hold the top of the unit against the top wall of a food compartment. The bottom side of the housing is closed by wall 54 and a partition comprising two walls 65 and 66 is provided to divide the housing into an upper and a lower section, the

walls at and 6t forming a dead air space between the sections to limit the how of heat from the lower section to the upper section. The upper section may be closed by a door 61 and the lower section by a door 68, the doors being shown only in Fig. 6. In order to refrigerate the side walls-of the housing; I provide headers 69, I0 and H formed by complementary indentations in the inner and outer sheets 59 and $0, the headers 69 and 10 being maintained about half full of liquid refrigerant and connected above the normal liquid level therein by a passage 12 andbelow the normal liquid level by a passage It. The headers 10' and II are connected by similar passages 14 and 15 above and below the liquid level respectively. In order to circulate liquid refrigerant in the wall on the side in which is formed the header 69, I providesubstantially vertical passages 16 and 11 formed in the outersheet 60 and communicating at their upper ends with the header G9 and a plurality of substantially parallel inclined transverse passages I8 formed in the inner sheet 59 and extending from the passage 16 to the passage 11. The ends of the passages 18 communicate with the passage 16 at a higher level than the ends communicating with the passage TI, which produces a tendency for refrigerant vaporized in the passages It to flow into the passage 16 and thereby produce some naturalcirculation of refrigerant from the passage 11 to the passage I6. In order to induce a positive circulation in the passages I8, I inject refrigerant upwardly into the passage lfi in the bottom thereof through an injector it. This produces a rapid upward circulation of refrigerant in the passages 16 and induces a flow of refrigerant through the passages it toward the passagelt and thence to the header 69, the liquid refrigerant returning to the passages 18 through the passage "H. The walls Liquid refrigerant is admitted to the cooling unit through liquid line 8|] which corresponds to the double liquid lines If! shown in Fig. 1. The liquid refrigerant flows from the line 80 into a manifold M formed in the outer sheet fill and substantially parallel to the transverse passages it, 18a, and 'i8b, and the injector ducts 19, 19a,

and 1% connect the manifold Bi with the upright passages "l6, 16a, and 15b respectively, and thereby produce a circulation of refrigerant on all three sides of the housing.

The several passages and the headers in the sheets 59 and 6B) are formed while the sheets are 11%. The sheets are then secured together by welding or brazing or in any other suitable manner around the edges, and between the in dentations, and are then bent to form the three sided housing as shown. It will be evident that since the pat-magic M, Ma and it?) are arranged in alinement and on the opposite side of the structure from the upright passages, the sheets tit and 6!) may be secured togetherby line welds formed along the sides of the passages i3, 18a and 18b by a welding wheel which may traverse the three walls of the evaporator without being.

. i. i, l

closed in'Fig's. 5,8 an'd' 'f is described and claimed in my copending application Serial No. 285,102,

filed July '21, 1939, which is a division of my pres ent application.

In order to provide freezing capacity, an evap- I orator 83 is arranged within the upper section of the housing as shown in Fig. 6, the evaporator 83 being shown removed from the housing in Fig. 5. This evaporator may be of any suitable form. However, I prefer to use an evaporator of the type shown and described in application Serial No. 51,846, filed November 27, 1935, in the name of Leonard W. Atchison, and assigned to the General Electric Company, assignee of my present invention. The evaporator 83- comprises a header 84 formed between inner and outer complementary sheets 85 and 85. A plurality of passages 81 open into the header 84 at their upper ends and extend downwardly over a side wall below the header and over the bottom wall of the evaporator. Liquid and gaseous refrigerant is admitted to the evaporator through a connection 88 and flows through a series conduit 88, portions of which are shown in Fig. 5 on theside wall of the evaporator opposite the header. From theconduit 88, the liquid and vaporized refrigerant flows through a manifold (not shown) into the conduits 81 to produce a circulation of refrigerant in the conduits 81. A dummy wall or extension 88 is provided to enclose an upper compartment of the evaporator 83 and also provide a flange 8| which cooperates with a flange 82 above the header 84 to provide a support, whereby the evaporator 88 may be secured to the top wall of the refrigerator cabinet. The series conduit 88 extends over the area of a shelf 83 and evaporator 83 therefore provides two freezing shelves and constitutes a freezing chamber. When the evaporator 83 is mounted within the upper section of the housing of the cooling uni-t, the walls of the evaporator are spaced from the walls of the housing and from the partition 86. Liquid or gaseous refrigerant flows from the header 18 through a connection 84 and an adjustable throttling valve 85 to the connection 88 and thence into the evaporator 83.

The connection 84 opens into the header 18'nearv the normal level of liquid refrigerant therein and both liquid and gaseous refrigerant are, therefore, withdrawn from the header 18 in the same manner as from 'the header 38 of the evaporator shown in Fig. 2. Gaseous refrigerant is withdrawn from the header 84 above the level of liquid refrigerant and hence from the cooling unit through a suction line 88 corresponding to the suction line 28 shown in Fig. 1. The valve 85 is mounted in a U-shaped bracket 81 which is secured to a cross panel 88 mounted in the upper front portion of the cooling unit as indicated in Fig. 6, the panel being shown removed in Fig. 5.

The construction of the valve 85 is clearly shown inFig. 7, where I have indicated the valve bracket 81 secured by screws 88 to the panel 88. The valve 95 is'similar to the valve 5| shown in -Fig. 4 in that an arrangement is provided so that the valve may not be closed entirely and at least a minimum flow of refrigerant is afforded at all times. Valve 85 comprises a valve block I88 secured in the bracket 91 bya threaded I84 is provided to vary the opening of the valve,

the limiting position of the stem being determined by shoulder I85 which maintains open a passage I88, so that the valve cannot be closed completely. The valve stem I84 is sealed against leakage by an expansible bellows I81, which maintains the seal during the axial movement of the stem. The valve may be adjusted by movement of a cam I88 against which a head I88 of the valve stem is pressed by a spring II8 within the bellows I81. The cam I88 is mounted in the end of the bracket 81 and may be rotated by a knob III having a pointer H2 to indicate the position of the valve. In Fig. 7, the valve is shown in its position of maximum opening. It is evident that the position of the valve stem I84 may easily be adjusted by turning the knob III and there is no danger of leak-age or loss of refrigerant since the bellows I81 maintains the valve sealed.

During the operation of the unit shown in Figs. 5, 6 and 7, refrigerant is admitted to the cooling unit through the liquid line 88 and flows into the walls of the outer housing through the manifold 8| and ducts 18, 18a and 1812 which produces a circulation of refrigerant in the transverse conduits 18, 18a and 18b and cools the air within the food compartment and also within the upper and lower sections of the housing. Liquid and gaseous refrigerant then flows through the connection 84 and the valve 85 to the inner evaporator 83 which constitutes the upper section of the housing a freezing compartment in which sufliciently low temperatures are maintained for the freezing of water, desserts and the like. The gaseous refrigerant is discharged from the cooling unit through connection 88 and returned to the refrigerating machine in the same manner as was described with regard to the cooling unit shown in Fig. 1. Valve 85 maintains a difierential ofv pressure between the inner and outer evaporators in the same manner as the valve 5| of Figs. 1 to 4 inclusive, and the lower section of the housing of the cooling unit is maintained at a temperature intermediate the temperatures of the freezing chamber and food compartment in the same manner as the temperature is maintained in the lower compartment of the cooling unit shown in Fig. 1.

Both of thecooling unitsdescribed above are preferably arranged within a refrigerator cabinet so that they are spaced from the side and back walls thereof and afford a free circulation of the air of the food compartment over the evaporator. The large cooling area thus provided, makes it possible to operate the outer portion of the evaporator at much higher temperatures than are required to maintain the desired air temperatures with a small evaporator surface. The doors provided for the cooling units prevent the circulation of the food compartment air over the intensely cooled portions of the cooling unit and thereby reduce to a minimum, the dehydration of food and air contained in the main food compartment. Meats and similar comestlbles are kept for substantially longer periods in the lower portions of the cooling units constructed as shown, and are not subject to dehydration and discoloration which results when these foods are placed in higher temperature compartments, such as the main food compartment. In both the modifications illustrated, the refrigerating machine is preferably controlled by a thermostatic elementsuch as the element 22 shown in Fig. 1 secured in the main wall of the housing of the cooling unit, so that the operation of the refrigerating machine is controlled in response'to the temperature of the higher pressure evaporator. The valves shown in Figs. 4 and 7 may easily be adjusted to maintain the desired difference of temperatures and are so constructed that some refrigerating capacity is available in both evaporators of the cooling unit at all times.

While I have shown particular embodiments of my invention in connection with a household refrigerating machine, other modifications will readily be apparent to those skilled in the art. I do not, therefore, desire my invention to be limited to the constructions shown and described. and I intend in the appended claims to cover all modifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

l. A refrigerating machine including a cabinet having a food compartment to be cooled, a cooling unit arranged within said compartment, said cooling unit comprising a housing forming a closed chamber, means for dividing said chamber into a plurality of sections and for partially insulating two of said sections from each other. means including a refrigerant conduit arranged on the walls of said housing for cooling the air within said food compartment and for cooling the walls of said two of said sections, means associated with one of said two sections for constituting said one of said two sections a freezin chamber, said last-mentioned means including a freezing shelf adapted to contain refrigerant means for supplying refrigerant to said conduit and to said shelf and for withdrawing refrigerant therefrom, and means for maintaining a higher pressure of refrigerant in said conduit than in said shelf whereby the other of said two sections is maintained at a temperature intermediate that of said food compartment and that of said freezing chamber.

2. A refrigerating machine including a cabinet having a food compartment to be cooled, a cooling unit arranged within said food compartment, said cooling unit comprising a housing forming a closed chamber, means for dividing said chamher into a plurality of sections and for partially insulating two of said sections from each other, means including a refrigerant conduit arranged on the walls of said housing for cooling the air within said food compartment and for cooling the walls of said two of said sections, means associated with one of said two sections for con stituting said one of said two sections a freezing chamber, said last-mentioned means including a shelf adapted to contain refrigerant, means for supplying refrigerant to said conduit and to said shelf and for withdrawing refrigerant therefrom, and means for maintaining said conduit at a higher temperature than said freezing shelf whereby the other of said two sections is maintained at a temperature intermediate that of said food compartment and that of said freezing chamber.

therefrom, and means for maintaining said con- 3. A refrigerating machine including a cabinet having a food compartment to be cooled, a cooling unit arranged within said food compartment, said cooling unit comprising a housing forming a closed chamber, means including a refrigerant 5 conduit arranged on the walls of said housing for cooling the air within said compartment and for cooling the walls of said chamber, means including a refrigerant evaporator for dividing said chamber into atleast two sections partially 10 insulated from one another and for providing a freezing chamber in one of said sections, means for supplying refrigerant to said conduit and to said evaporator and for withdrawing refrigerant 1 5 duit at a higher temperature than said evaporator whereby the other of said two sections is maintained at a temperature intermediate that of said food compartment and that of said freez ing chamber.

4. A refrigerating machine including a cabinet having a food compartment to be cooled, a cooling unit arranged within said food compartment, said cooling unit including a wall having a refrigerant conduit arranged thereon for cooling the air within said food compartment, means including a freezing shelf adapted to contain refrigerant for providing a freezing surface, means connecting said refrigerant conduit and said freezing shelf for conveying refrigerant from said conduit to said shelf, means for supplying refrigerant to said cooling unit and for withdrawing refrigerant from said freezing shelf, means including an adjustable valve arranged in said connecting means for maintaining said con- 5 duit at a higher temperature than said shelf, and

means for afiording at least a restricted measure of communication between said conduit and said shelf at all times.

5. A refrigerating machine including a cabinet 40 having a food compartment to. be (200165198. cooling unit arranged within said food compartment, said cooling unit comprising a housing forming a closed chamber, means for dividing said chamber into a plurality of sections, means including a refrigerant conduit arranged on the walls of said housing for cooling the air within said food compartment and for cooling the walls of two of said sections, means associated with one of said two sections for constituting said one of said 5'0 two sections a freezing chamber, said last-mentioned means including a freezing shelf adapted to contain refrigerant, means connecting said refrigerant conduit and said freezing shelffor conveying refrigerant from said conduit to said shelf, means for supplying refrigerant to said cooling unit and for withdrawing refrigerant therefrom, means including an adjustable valve arranged in said connecting means for maintaining said conduit at a higher temperature than said shell, and means for afiording at least a restricted measure of communication between said conduit and said shelf at all times.

6. A refrigerating machine including a cabinet having a food compartment to be cooled. a condensing unit for supplying refrigerant, means including a cooling wall connected to receive refrigerant from said condensing unit and having a refrigerant conduit for cooling said food compartmcnt, means including a freezing shelf adapted to contain refrigerant for providing a freezing chamber for said refrigerating machine,

means connecting said refrigerant conduit and valve arranged in said connecting means for maintaining said conduit at a higher temperature than said freezing shelf, said valve including a valve block having a valve stem slidably mounted therein and an expansible bellows for sealing said valve against leakage of refrigerant, means including a cam for adjusting the position of said valve stem to vary the relative pressures in said refrigerant conduit and said freezing shelf, means for maintaining said valve partially open at'all times, and means for returning to said condensing unit refrigerant vaporized in said cooling wall.

7. A refrigerating machine including a cabinet having a food compartment to be cooled, a cooling unit arranged within said food compartment,

7 said cooling unit comprising a housing forming a. closed chamber, means for dividing said chamber into a plurality of sections and for partially insulating two of said sections from each other, means including a refrigerant conduit arranged on the walls of said housing for cooling the air within said food compartment and for cooling the walls of said two of said sections, means including a freezing chamber having Walls adapted to contain refrigerant and arranged in one of said two sections for constituting said one section a freezing compartment, the walls of said freezing chamber being spaced from the walls of said one section, means for supplying refrigerant to said conduit and to said walls of said freezing chamber and for withdrawing refrigerant therefrom, and meansfor maintaining said conduit at a higher temperature'than the walls of said freezing chamber whereby the other of said two sections is maintained at a temperature intermediate that of said food compartment and that of said freezing compartment.

, 8. A cooling unit for refrigerating machines comprising a housing forming a closed chamber, means for dividing said chamber into a plurality of sections, a refrigerant conduit arranged on the walls of said housing for cooling the air surrounding said housing and for cooling the walls of two of said sections, means associated with one of said'two sections for constituting said one of said two sections a freezing chamber, said lastmentioned means including a freezing shelf partially insulated from the other of said two sec tions and adapted to contain refrigerant, an inlet connection for conducting refrigerant to said conduit and an outlet connection for conveying refrigerant withdrawn from said cooling unit, and means adapted to cooperate with the condensing unit of a refrigerating machine for maintaining said conduit at a higher temperature than said freezing shelf whereby the other of said two sections is maintained'at a temperature intermediate that of the freezing chamber and of the air surrounding said housing.

9. A cooling unit for refrigerating machines comprising a housing forming a closed chamber, means for dividing said chamber into a plurality of sections, means including a refrigerant conduit of the flooded type arranged on the walls of said housing for cooling the air surrounding said housing and for cooling the walls of two of said sections, means associated with one of said two sections for constituting said one of said two sections a freezing chamber, said last-mentioned means including a freezing shelf adapted to contain refrigerant, means connecting said conduit and said freezing shelf for conveying refrigerant to said shelf, an inlet connection for conducting refrigerant to said cooling unit and an outlet connection for conveying refrigerant withdrawn from said cooling unit, means including an adjustable valve arranged in said connecting means adapted to cooperate with the condensing unit of a. refrigerating machine for maintaining said conduit at a higher temperature than said shelf, and means for affording at least a restricted measure of communication between said conduit and said shelf at all times.

CHRISTIAN STEENSTRUP.

CERTIFICATE OF CORRECTION. Patent No. 235L711. March 11, 19in.

' CHRISTIAN STEENSTRUP.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, sec- 0nd column, line 15, for "letter d" read -letter a--; page 5, first column', line Mi, claim 1, after the word- "refrigerant" insert a comma; and that the said Letters Patent should be read with this correction therein that the same may conform to the record ofthe case in the Patent Office;

Signed and sealed this 15th day of April, A. D. 1914.1.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents. 

